1. Field of Invention
The present invention relates to the general art of watercraft, and to the particular field of control means for hybrid-electric powered watercraft incorporating manual (pedal, human) power with electric power amplification.
2. Description of Prior Art
A multitude of pedal-powered watercraft (also referred to as water bikes, water-bicycles, and watercycles) are commercially available. They are relatively low cost, low maintenance, light weight, and fun. Their main drawback is the relatively low power output capability of the operators. Unlike watercraft propelled by conventional combustion engines, pedal-powered watercraft are severely limited in power capability; typically less than 200 watts (around ¼ hp) per person on a continuous basis. A cyclist in good condition can generate around 200 watts at a preferred cadence of around 90–100 RPM. Many people of lesser abilities may be only capable of generating around 100 watts in a continuous comfortable manner. Thus maximizing the overall efficiency of the watercraft, including its propulsion system, as it travels in water is vitally important to maximize speed and travel distance capabilities. To maximize the speed (and pedaling efficiency), many of the newer watercycles such as the Seacycle® and Waterbike® manufactured by the Meyers Boat Company, Inc., are designed to be lightweight with efficient long and narrow hulls.
U.S. Pat. No. 6,855,016 (Jansen) discloses an electric watercycle incorporating electrical power generation from human kinetic power, and electrical energy storage to enable amplification of human-power to propulsion power to achieve increased watercraft speeds. Control electronics enable operator-adjustable variable electronic gearing, and an assortment of torque vs. speed loading characteristics of the generator, thereby providing optimal pedal cadences and enjoyment for a wide variety of operators. An optional photovoltaic solar panel augments the power generation to extend travel time with power amplification, and recharges the energy storage system. This invention provides a pleasure watercraft that is simultaneously lightweight, low cost, low maintenance, environmentally friendly with zero pollution, ultra-low noise, and thrilling to operate, while simultaneously providing a means of enjoyable exercise for operators of nearly all abilities.
One additional drawback of the existing watercycles, including the electrical watercycle, is that the mechanical properties such as rotational inertia as perceived by the operator at the input pedal mechanism is unlike that of bicycles. The pedaling effort is often felt to be jerky and not nearly as enjoyable as pedaling a bicycle. Two of the main causes of this are a reduced rotational inertia, and a lack of a freewheeling clutch mechanism, in most watercycles of the prior art.
U.S. Pat. No. 6,217,398 B1 (Davis) discloses a human-powered or human-assisted energy generation and transmission system with energy storage means and improved efficiency. The generation and transmission system is intended to be an improvement over conventional mechanical systems, such as pedal-powered systems comprising chains and sprockets, by controlling the energy output to be constant, independent of the pedal position, thereby claiming to improve the overall efficiency. Over a typical pedal cycle, the power produced by a human varies substantially with pedal position. According to the Davis invention, energy storage is used to supplement the human power during the portion of the pedaling cycle that is least efficient. This portion of the pedal cycle is determined by sensors detecting the pedal position during rotation. The supplemental energy is extracted from the energy generated during the portion of the pedaling cycle that is most efficient, such that the average energy generated and used for propulsion is not increased, apart from potential claimed efficiency improvements. The generation and transmission system consists of electric generators, motors, energy storage, controllers, and sensors, without mechanical linkages. The intended applications are human-powered or human-assisted vehicles of all types, including bicycles, watercraft, aircraft, hydrofoils, and hovercraft.